Description of problem:
Using "-i" option will wait in an unexpected way (even when data is transmitted)


Version-Release number of selected component (if applicable):
nmap-ncat-6.40-4.el7.x86_64


How reproducible:
always


Steps to Reproduce:
Objective: 
- using nc to connect to a remote system
- send a string to the remote system
- get a string back from the remote system and exit
- set a max timeout for the entire operation so that if the remote system answers back in say 0.1 sec, nc will exit after 0.1 sec, in any other case (remote system not online, remote system connects but doesn't answer back, whatever) the nc command will exit in a fixed amount of time.

With RHEL5/6 nc, we had 
	"-w" (for connect and idle timeout)

With RHEL7 (switch to nmap-ncat) we have 
	-w (for connect timeout)
	-i (for idle timeout)
but "-i" doesn't work as I would expect.


Actual results:
Connecting from RHEL7 (will wait 3 secs)
$ time echo quit | nc -w 3 -i 3  ip.local.lan 21
220 (vsFTPd 2.0.5)
221 Goodbye.
Ncat: Idle timeout expired (3000 ms).
 
real    0m3.054s
user    0m0.005s
sys     0m0.009s
$


Expected results:
Connecting from RHEL5/RHEL6 (exits as soon as possible)
$ time echo quit | nc -w 3 ip.local.lan 21
220 (vsFTPd 2.0.5)
221 Goodbye.
 
real    0m0.008s
user    0m0.000s
sys     0m0.001s
$


Additional info:
If you omit "-i" it will exit immediately, but then when the server has problems and doesn't answer back the connection will be stuck and won't terminate in a fixed amount of time.